This invention relates to antennae and in particular to high-performance antennae for use in hand-held and similar portable equipment such as hand-held radio telephones.
The specific application of this invention is in a CT2 digital cordless telephone operating at 864-868 MHz. The style of the phone is a small handset, with a hinged flap which opens to reveal a keypad. When the handset is not in use, the flap is closed to reduce the phone size and conceal the keypad.
FIGS. 1 and 2 of the accompanying drawings show a typical handset, one or more of which may be potentially in communication with a base unit (not shown) incorporating a transceiver, together with interface circuitry for connection to an associated telephone network. The handset electronics, including a transceiver and associated antenna for communicating with the base unit, is contained within a housing 1 of plastic material. A hinged flap 2, shown in the open position in FIG. 2, allows access to a keypad 3.
In such a system, it is clear that radio performance will be inherently degraded by placing the handset against an obstacle. In the case of a telephone, the handset is always against the users head when the phone is in use. This causes attenuation which is especially apparent at high frequencies, such as those of cellular and CT2 systems. It is possible to add an external antenna to the handset to reduce the effect by moving the antenna a small distance away from the head. This invention specifically provides an antenna system within the body of the handset, providing improved performance without the need for an external antenna. It also efficiently provides antenna switching without the need for any additional components.